I have two free books, one on amazon.com and one on amazon.co.uk (two days ago). The book on the dot com site is literary fiction and downloads were pretty rapid: 2,800 in twenty-four hours. The downloads slowed yesterday to just over 700. The total as I write this post is 3,530.
http://www.amazon.com/The-Power-of-Persuasion-ebook/dp/B0050UQJJQ/
The ranking has fallen from #33 (highest) in all free Kindle books to #88
It has also lost top spot in the category "literary fiction" -- it was #1 in Kindle Store > Kindle eBooks > Fiction > Literary Fiction (now #2).
On amazon.co.uk,
Four Short Stories downloads began much, much, much more slowly: only 22 downloads in the first twenty-four hours. With all the protests on the Amazon forums, it was difficult to even give my books away! With so few downloads, I decided to risk starting a new thread on the Kindle forum (UK) and the downloads picked up. As I write, the total is 145.
http://www.amazon.co.uk/Four-Short-Stories-ebook/dp/B004NIFTHY/
The ranking has improved steadily and the book is now just out of the top 100 free (#11

in Kindle store, and it is #5 in Kindle Store > Books > Fiction > Short Stories
By the time you read this post, the rankings may have changed! Amazon updates hourly.